The invention relates generally to a multicolored, patterned floor covering and a method for its manufacture. The floor covering is of the type which typically has a thickness of 1 to 4 mm, and consists of a sheeting having a first color that contains an imbedded granulated material dyed to a second color that differs from the color of the sheeting. The granulated material is embedded in the sheeting in at least the upper side of the sheeting. Such a floor covering is disclosed in French patent FR-PS 11 67 760, which lists a number of thermoplastic, polymer materials usable for this purpose, with polyvinyl chloride (PVC) being preferred.
The French patent also describes a method for manufacturing such a floor covering, particularly from PVC, in which at least two differently colored fractions of raw material are converted into sheeting using two rollers having identical diameters turning inversely at the same speed. Concomitantly, granular materials are forced under pressure into a thermoplastic base material, which is then heated to at least the softening point of the base material and again pressed, so that the base material completely surrounds the particles.
One problem arising from the manufacture of such floor coverings is that the pieces of waste material such as border trimmings and production remnants that are produced by such methods are characterized by the respective colors that are utilized. Consequently, they are not reusable in the same production process, and are usable to only a limited extent for the production of other recycled products.
This invention is directed to the problem of providing a floor covering of this general type, and a method for its production, such that the pieces of waste material that are produced through the manufacture of the floor covering can be reused in the same process.
The invention solves this problem by providing a patterned floor covering having a thickness of 1 to 4 mm, in which sheeting comprises a matrix having a first color and to which a quantity of contrastingly colored particles is added. Both the matrix sheeting material and the contrastingly colored particles are made of cross-linkable elastomeric materials. The contrastingly colored particles have a plurality of dissimilarly colored sections that also differ in appearance from the matrix material. The amount and color of the particles and the sections within the particles are so selected and harmonized with respect to the quantity and color of the material forming the sheet matrix that the overall mixed color effect from intermixing the components is itself consistent with respect to the matrix color. In other words, while the added particles may, individually, contrast with respect to the surface of the matrix sheeting material in which they are imbedded, they are provided in overall quantities and color such that when remnants of the finished sheeting containing the added particles are reduced to particulate material, they can be recycled into matrix material for use as additional sheeting. The coloration of the imbedded particles and their quantity is not so great as to contrast unduly with the virgin matrix sheeting material with which the process is begun.
It is to be understood that the recycled material will agree in coloration with the virgin matrix material in the general sense, and that the latter may be combined with the former or used alone as matrix even though it may not be exactly identical in appearance to the virgin matrix material, and even though slight color variations between the mixed color and the first color may be detectable optically or by using measuring technology. This does not constitute an obstacle to the practical utilization of this material in recycling within the process. This is especially true when one considers that in a typical large-scale industrial process, the recycled remnants that are used may constitute merely a fraction of the total quantity of matrix material employed to produced new sheeting.
By utilizing elastomeric materials for all of the components of the covering, the floor covering obtained possesses excellent mechanical properties. Moreover, these properties are easy to control, as the matrix material which forms the sheeting is of homogenous composition, and completely surrounds the particles embedded therein (with the exception of the particle surfaces which face the working surface of the floor covering). In addition, by eliminating the production of unrecyclable waste material, the floor covering can be manufactured in a particularly cost-effective manner.
The particles that are added to the matrix can comprise at least three zones varying in coloration from the adjoining zones of the particle. This permits one to vary the appearance of the floor covering to a great extent to suit a wide array of tastes.
The particles can be arranged so close to one another that they touch. In this embodiment, the outer appearance of the floor covering is determined substantially by the structure and dying of the particles.
However, it is also possible to arrange the particles so that they are spaced apart from each other. In this embodiment, the outer appearance of the floor covering is determined substantially by the color of the sheeting, with the particles serving to provide the effect of xe2x80x9cbreaking upxe2x80x9d the appearance of the sheeting.
The particles can be distributed in a randomized pattern or in an arbitrarily selected ordered pattern. For example, the particles may be distributed in the sheets to present the form of letters, words, or pictographs.
Such detailed distribution of particles requires that one be able to precisely distribute the particles into the matrix forming the sheet. This is best done by limiting the distribution of particles so that they are embedded only in the top side and/or in the bottom side of the sheeting. In such a variant, it is advantageous that the quantity of particles embedded in the top side of the sheeting be greater that the quantity of particles embedded in the bottom side. The discrete color surfaces visible in the area of the top side should have a size of between 1 to 25 mm2, it being preferable that the contrastingly-colored particles and particle sections be present in a quantity of between 80 to 450 g/m2, relative to the weight of the material body forming the sheeting.
The method set forth in FR-PS 11 67 760 is not well suited to the manufacture of a floor covering that, like the floor covering of the present invention, is made of rubber. Accordingly, a further goal of the invention is to further develop the known method so that to permit the manufacture of a floor covering made of rubber.
In the method of the invention, a contrastingly-colored granular material made of caoutchouc is introduced into a sheeting of caoutchouc that has previously been homogeneously dyed to a first color. The granular material comprises particles which include at least two particle sections dyed differently both from each other and from the sheeting and which are permanently set in position by means of subsequent vulcanization into the sheeting. In its final, ready-to-use state, the floor covering is no longer capable of being thermally softened, and possesses great chemical, mechanical and thermal stability. The sheeting is harmonized with respect to the quantity and color of the caoutchouc of which it is formed with respect to both the quantity and the color of the particles and particle sections contained in the granular material. This is done so that the mixed or composite color effect resulting from the homogenous intermixing of all the components added to the floor covering agrees with the color of the original sheet matrix, thereby facilitating the use of sheet remnants in recycled form. Hence, the floor covering can be produced cost-effectively while avoiding the production of any waste material.
In accordance with one advantageous refinement, the sheet or matrix is formed from a feed of a first granular rubber material having a first color that is fed directly from above into a gap between two horizontally counter-rotating rollers. This material is also mixed with a contrastingly-colored second granular material. The bulk material thus obtained is compressed in the opening or nip of the rollers in a non-porous manner while avoiding a mutual intermixing of the color boundaries of the particles forming the granular materials. At the same time, the second granular material preferentially is fed to the first granular material at a site that is displaced relative to the middle of the opening, towards or away from one or the other rollers. This minimizes its exposure to the considerable shear forces which arise in the middle of the opening. The production of precisely patterned floor covering which the invention affords and its lack of blurred colors follows from this aspect of the invention.
In another aspect of the invention, a contrastingly-colored granular material made of caoutchouc is sprinkled on a sheeting of caoutchouc dyed in a first color. The granular material comprises particles having particle sections which are dyed differently from the sheeting, the sheeting and the granular material being so harmonized with each other with respect to quantity and color that the mixed color resulting from an homogeneously mixing all of the components contained in the floor covering (as would happen should one reduce any scrape so produced back into particle form) agrees with the first color. In a subsequent step, the particles are pressed into the sheeting so that they are flush with the surface. This is accomplished by means of a roll calendar, a continuous vulcanizing machine or a press at a temperature of 160xc2x0 C. to 190xc2x0 C., in which the position of the added granular material is fixed with respect to the sheet of matrix material by the subsequent vulcanization of the caoutchouc. The mechanical stress of the contrastingly-colored particles and particle sections is particularly insignificant in the case of such a method, which facilitates the production the production of patterns which are free from blurred colors in the visible surface portions of the floor covering.
All elastomeric materials which are suitable for the manufacture of floor covering, such as, SBR (styrene butadience rubber), NBR (nitrile-butadiene rubber), EPDM (a terpolymer elastomer made from ethylene-propylene diene monomer) or natural rubber, as well as mixtures of these, can be used within in the present invention.
The colored granular material that is employed to provide contrast with the color of the sheeting can be obtained by producing contrastingly-colored rubber mixtures independently of each other, converting them into the form of strands using extruders, and subsequently granulating them. The variously colored fractions of the individual granular substances are then combined according to quantity and color and allocated in the sheeting that has been dyed in the first color so that, in an homogeneous intermixing of all the components, the color of the sheeting again results. Of course, such an intermixing or homogenization is only undertaken if, in the manufacture of the floor covering, waste products remain which should be fed once more into the production process.
It is also within the scope of this invention to use a single extruder to jointly convert the contrastingly-colored rubber mixtures, produced independently of each other, into the form of varicolored strands and subsequently to granulate these and sprinkle them on the sheeting that has been dyed to a first color in such a quantity and color distribution of the fractions that the mixed color resulting from an homogenous intermixing of all the components contained in the product agrees with the first color. With regard to the manufacture of multicolored particles of this kind, it is merely important that contrastingly-colored rubber mixtures utilized for their manufacture be prevented from mutual intermixing in the area of the color boundaries during the processing in the extruder. This can be achieved by mixing in an extruder under particularly careful conditions. With this caveat in mind, it should be particularly noted that temperatures of more than 100xc2x0 C. should be avoided, as should other stresses which can lead to a complete decomposition of the rubber mixtures used.
The method according to the invention allows the contrastingly-colored granular materials to be particularly well integrated into the material body forming the sheeting, so that in the mandrel bending test according to DIN 51949, using a mandrel having a diameter of 20 mm and a material thickness of the sheeting of 2 mm, no separation is to be observed at the grain boundary between the particles embedded in the sheeting and the base (matrix) material. The particles, vulcanized into the sheeting in a manner that they are flush with the surface, form with the surface of the sheeting a single gap-free surface.
The waste resulting from the production of the floor covering according to the invention can be reused in any quantity as needed in manufacturing a floor covering which completely agrees with the floor covering manufactured initially. Hence, the economies of this process are very advantageous.